For example, a patent document 1 and so on discloses an evaporated fuel processing device arranged to temporarily store an evaporated fuel generated in a fuel tank in a canister and so on, to purge the evaporated fuel during drive of the engine, and to introduce the evaporated fuel to an intake system.
In particular, the patent document 1 relates to the evaporated fuel processing device of the internal combustion engine provided with a turbocharger. The patent document 1 has a configuration including a main purge passage arranged to introduce the evaporated fuel purged from the canister to a portion downstream of a throttle valve in a non-supercharging (non-pressure-charging) region; and a sub purge passage arranged to introduce the evaporated fuel to a portion upstream of a compressor of the turbocharger in a supercharging (pressure-charging) region in which the introduction to this downstream portion of the throttle valve cannot be performed.
On the other hand, conventionally, the various type variable compression ratio mechanisms arranged to vary a mechanical compression ratio of the internal combustion engine has been known. For example, the present applicant has proposed a variable compression ratio mechanism arranged to displace a piston upper dead center in the upward and downward directions by varying a link geometry of the multi-link type piston crank mechanism. Moreover, there is known a variable compression ratio mechanism arranged to similarly vary a mechanical compression ratio by displacing a position of the cylinder with respect to the center position of the crank shaft in the upward and downward directions.
In the evaporation fuel processing device, a storage portion such as a canister which temporarily stores the evaporation fuel has, as a matter of course, a constant capacity (volume). It is not preferable that the evaporated fuel is accumulated to exceed this capacity, since the evaporation fuel outflows to the outside. Accordingly, it is necessary to surely purge during the drive of the internal combustion engine.
However, the maximum amount of the evaporated fuel which can be introduced into the intake system of the internal combustion engine is limited to the constant (some) rate with respect to the intake air quantity so that the deterioration of the controllability of the air fuel ratio is avoided, so that the fuel injection amount from the fuel injection valve is not smaller than the minimum injection amount, and so on. Accordingly, in a case where the frequency of the purge is small, it is not possible to sufficiently purge.
In particular, in a case where the internal combustion engine is provided with a turbocharger, in a supercharging (pressure-charging) region in which the pressure becomes the positive pressure, it is not possible to introduce the evaporated fuel to a portion downstream of the throttle valve. Accordingly, the opportunity of the purge becomes small. The purge is easy to become insufficient relative to the natural intake engine. In the patent document 1, the sub purge passage is provided. With this, the purge is performed in wider driving region. However, this may cause the complication of the configuration.